50890-67-0Relevant articles and documents
Can Donor Ligands Make Pd(OAc)2a Stronger Oxidant? Access to Elusive Palladium(II) Reduction Potentials and Effects of Ancillary Ligands via Palladium(II)/Hydroquinone Redox Equilibria
Bruns, David L.,Musaev, Djamaladdin G.,Stahl, Shannon S.
supporting information, p. 19678 - 19688 (2020/12/18)
Palladium(II)-catalyzed oxidation reactions represent an important class of methods for selective modification and functionalization of organic molecules. This field has benefitted greatly from the discovery of ancillary ligands that expand the scope, reactivity, and selectivity in these reactions; however, ancillary ligands also commonly poison these reactions. The different influences of ligands in these reactions remain poorly understood. For example, over the 60-year history of this field, the PdII/0 redox potentials for catalytically relevant Pd complexes have never been determined. Here, we report the unexpected discovery of (L)PdII(OAc)2-mediated oxidation of hydroquinones, the microscopic reverse of quinone-mediated oxidation of Pd0 commonly employed in PdII-catalyzed oxidation reactions. Analysis of redox equilibria arising from the reaction of (L)Pd(OAc)2 and hydroquinones (L = bathocuproine, 4,5-diazafluoren-9-one), generating reduced (L)Pd species and benzoquinones, provides the basis for determination of (L)PdII(OAc)2 reduction potentials. Experimental results are complemented by density functional theory calculations to show how a series of nitrogen-based ligands modulate the (L)PdII(OAc)2 reduction potential, thereby tuning the ability of PdII to serve as an effective oxidant of organic molecules in catalytic reactions.
Oxidation of 1,10-Phenanthroline by Tetraoxomanganate (VI) and (VII). Preparation, Structure and Properties of 1H-Cyclopentadipyridine-2,5-dione
Baxter, Paul N. W.,Connor, Joseph A.,Wallis, John D.,Povey, David C.,Powell, Anne K.
, p. 1601 - 1606 (2007/10/02)
Oxidation of 1,10-phenanthroline with tetraoxomanganate (VI) gave good yields of ketone 3 and the previously unknown dione 5, formed by the unusual further oxidation of 3 at the 2 position of a pyridine ring.In contrast, use of the tetraoxomanganate (VII) gave the bipyridine diacid 2 (69percent), ketone 3 (20percent) and only a trace of the dione 5.The X-ray crystal structure of the anion of 5 indicates that the negative charge is located mainly on the 2-O rather than 5-O atom, with some delocalisation into the pyridine ring.
